Svetlana's game is tailor made for grass and she proved that in her victory at Eastbournein 2004. She then lost inexplicably to Virginie Razzano in the first round of Wimbledon. She also beat Sharapova at Wimbledon on her way to the quarters in 2003.
I don't think it's appropriate however to assess her chances based on her performances there in previous years. Last year her game was in crisis and since then she has given her mental approach a total overhall. Svetlana will take some beating at Wimbledon and she has to be one of the favourites for the title.